In the present invention, a demodulation reference signal is transmitted using a plurality of settings in which demodulation reference signals occupy different positions in at least a density or time-frequency resource region of the demodulation reference signals. A base station can transmit, to the user device, information indicating a setting related to a downlink signal or a setting related to an uplink signal from among the plurality of settings, and the user device can receive the demodulation reference signal with the downlink signal or transmit the demodulation reference signal With the uplink signal according to the indicated setting.
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1. A method for receiving a downlink signal by a user equipment, the method comprising: obtaining, by the user equipment, first indication information indicating a first demodulation reference signal (DMRS) configuration from among a plurality of DMRS configurations defined for DMRS transmission; receiving, by the user equipment, a DMRS for the user equipment in a time-frequency resource region, to which the downlink signal for the user equipment is mapped, according to the first DMRS configuration indicated by the first indication information; demodulating, by the user equipment, the downlink signal using the DMRS; obtaining, by the user equipment, second indication information indicating that the first DMRS configuration is to be switched with a second DMRS configuration; and using, by the user equipment, a default DMRS configuration during a time interval when it is unclear whether to use the first DMRS configuration or the second DMRS configuration, wherein the plurality of DMRS configurations differ in a density of the DMRS, wherein the plurality of DMRS configurations include the default DMRS configuration, and at least a DMRS configuration of a lower density than a density of the default DMRS configuration or a DMRS configuration of a higher density than the density of the default DMRS configuration, and wherein the DMRS configuration of the lower density is defined to include only some resource elements (REs) for the DMRS among DMRS REs of the default DMRS configuration and the DMRS configuration of the higher density is defined to include predetermined DMRS REs in addition to the DMRS REs of the default DMRS configuration.
A user device receives a downlink signal by first obtaining information indicating which Demodulation Reference Signal (DMRS) configuration to use from a set of possible DMRS configurations. These configurations determine how DMRS signals are placed within the time-frequency resources allocated to the downlink signal. The device receives the DMRS according to the indicated configuration and uses it to demodulate the downlink signal. When the device receives information that the DMRS configuration is changing, it uses a default DMRS configuration during the transition period. The DMRS configurations vary in density, including a default density, a lower density (using only some resource elements of the default), and a higher density (using the default resource elements plus additional ones).
2. The method according to claim 1 , wherein the time-frequency resource region includes a plurality of physical resource blocks and at least one of the plurality of DMRS configurations is defined to include the DMRS only in some of the plurality of physical resource blocks.
In the downlink signal receiving method described previously, the time-frequency resource region is divided into multiple physical resource blocks. At least one of the DMRS configurations is defined to only include DMRS signals in a subset of these physical resource blocks. Therefore, some blocks may contain DMRS and some not, depending on the selected DMRS configuration.
3. A user equipment for receiving a downlink signal, the user equipment comprising: a radio frequency (RF) unit; and a processor that: obtains first indication information indicating a first demodulation reference signal (DMRS) configuration from among a plurality of DMRS configurations defined for DMRS transmission; controls the RF unit to receive a DMRS for the user equipment in a time-frequency resource region, to which the downlink signal for the user equipment is mapped, according to the first DMRS configuration indicated by the first indication information; demodulates the downlink signal using the DMRS; obtains second indication information indicating that the first DMRS configuration is to be switched with a second DMRS configuration; and uses a default DMRS configuration during a time interval when it is unclear whether to use the first DMRS configuration or the second DMRS configuration wherein the plurality of DMRS configurations differ in a density of the DMRS, wherein the plurality of DMRS configurations include the default DMRS configuration, and at least a DMRS configuration of a lower density than a density of the default DMRS configuration or a DMRS configuration of a higher density than the density of the default DMRS configuration, and wherein the DMRS configuration of the lower density is defined to include only some resource elements (REs) for the DMRS among DMRS REs of the default DMRS configuration and the DMRS configuration of the higher density is defined to include predetermined DMRS REs in addition to the DMRS REs of the default DMRS configuration.
A user device for receiving downlink signals has a radio frequency unit and a processor. The processor obtains information indicating which Demodulation Reference Signal (DMRS) configuration to use from a set of possible DMRS configurations. These configurations define DMRS placement in the time-frequency resources allocated to the downlink signal. The processor controls the RF unit to receive the DMRS according to the selected configuration and then demodulates the downlink signal using the received DMRS. When information is received indicating a DMRS configuration change, the processor uses a default DMRS configuration during the transition. The DMRS configurations vary in density, including a default density, a lower density (using only some resource elements of the default), and a higher density (using the default resource elements plus additional ones).
4. The user equipment according to claim 3 , wherein the time-frequency resource region includes a plurality of physical resource blocks and at least one of the plurality of DMRS configurations is defined to include the DMRS only in some of the plurality of physical resource blocks.
The user equipment described above is configured such that the time-frequency resource region consists of physical resource blocks. At least one DMRS configuration is defined to include the DMRS only in a subset of these physical resource blocks. The user equipment can use this configuration to receive DMRS in some physical resource blocks, but not others.
5. A method for transmitting a downlink signal by a base station, the method comprising: transmitting, by the base station, first indication information indicating a first demodulation reference signal (DMRS) configuration from among a plurality of configurations for DMRS transmission; transmitting, by the base station, a DMRS for a user equipment in a time-frequency resource region, to which the downlink signal for the user equipment is mapped, according to the DMRS configuration indicated by the first indication information; transmitting, by the base station, second indication information indicating that the first DMRS configuration is to be switched with a second DMRS configuration; and transmitting, by the base station, a default DMRS configuration during a time interval when it is unclear whether to use the first DMRS configuration or the second DMRS configuration, wherein the plurality of DMRS configurations differ in a density of the DMRS, wherein the plurality of DMRS configurations include the default DMRS configuration, and at least a DMRS configuration of a lower density than a density of the default DMRS configuration or a DMRS configuration of a higher density than the density of the default DMRS configuration, and wherein the DMRS configuration of the lower density is defined to include only some resource elements (REs) for the DMRS among DMRS REs of the default DMRS configuration and the DMRS configuration of the higher density is defined to include predetermined DMRS REs in addition to the DMRS REs of the default DMRS configuration.
A base station transmits a downlink signal by first transmitting information to a user device indicating which Demodulation Reference Signal (DMRS) configuration to use from a set of possible DMRS configurations. The base station then transmits the DMRS to the user device according to the indicated configuration, within the time-frequency resources allocated to the downlink signal. When the base station transmits information indicating that the DMRS configuration is changing, it transmits a default DMRS configuration during the transition. The DMRS configurations vary in density, including a default density, a lower density (using only some resource elements of the default), and a higher density (using the default resource elements plus additional ones).
6. The method according to claim 5 , wherein the time-frequency resource region includes a plurality of physical resource blocks and at least one of the plurality of DMRS configurations is defined to include the DMRS only in some of the plurality of physical resource blocks.
In the downlink signal transmitting method described previously, the time-frequency resource region consists of physical resource blocks. At least one of the DMRS configurations is defined to include the DMRS only in a subset of these physical resource blocks. Therefore, the base station may transmit DMRS in some blocks and not others, depending on the selected DMRS configuration.
7. A base station for transmitting a downlink signal, the base station comprising: a radio frequency (RF) unit; and a processor that: controls the RF unit to transmit first indication information indicating a first demodulation reference signal (DMRS) configuration from among a plurality of configurations for DMRS transmission; controls the RF unit to transmit a DMRS for a user equipment in a time-frequency resource region, to which the downlink signal for the user equipment is mapped, according to the first DMRS configuration indicated by the first indication information; controls the RF unit to transmit second indication information indicating that the first DMRS configuration is to be switched with a second DMRS configuration; and controls the RF unit to transmit a default DMRS configuration during a time interval when it is unclear whether to use the first DMRS configuration or the second DMRS configuration, wherein the plurality of DMRS configurations differ in a density of the DMRS, wherein the plurality of DMRS configurations include the default DMRS configuration, and at least a DMRS configuration of a lower density than a density of the default DMRS configuration or a DMRS configuration of a higher density than the density of the default DMRS configuration, and wherein the DMRS configuration of the lower density is defined to include only some resource elements (REs) for the DMRS among DMRS REs of the default DMRS configuration and the DMRS configuration of the higher density is defined to include predetermined DMRS REs in addition to the DMRS REs of the default DMRS configuration.
A base station for transmitting downlink signals has a radio frequency unit and a processor. The processor controls the RF unit to transmit information to a user device indicating which Demodulation Reference Signal (DMRS) configuration to use from a set of possible DMRS configurations. The processor controls the RF unit to transmit the DMRS to the user device according to the selected configuration, within the time-frequency resources allocated to the downlink signal. When the processor controls the RF unit to transmit information indicating a DMRS configuration change, it transmits a default DMRS configuration during the transition. The DMRS configurations vary in density, including a default density, a lower density (using only some resource elements of the default), and a higher density (using the default resource elements plus additional ones).
8. The base station according to claim 7 , wherein the time-frequency resource region includes a plurality of physical resource blocks and at least one of the plurality of DMRS configurations is defined to include the DMRS only in some of the plurality of physical resource blocks.
The base station described above is configured such that the time-frequency resource region consists of physical resource blocks. At least one DMRS configuration is defined to include the DMRS only in a subset of these physical resource blocks. The base station can use this configuration to transmit DMRS in some physical resource blocks, but not others.
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September 25, 2013
March 28, 2017
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